Microstructure and tribological properties of Y2O3-doped Fe-based alloy coatings by laser cladding

The laser-clad Fe45 alloy coating inherently comprises multiple crystalline phases, resulting in a heterogeneous microstructural distribution that influences its performance. In this study, the rare earth yttria (Y 2 O 3 ) was employed to modify laser-clad Fe45 alloy coatings, and the effects of Y 2 O 3 addition on their microstructure, microhardness, and tribological properties were investigated. As the Y 2 O 3 content increases from 0% to 0.3wt.%, the dominant microstructure transforms from columnar crystals to fine cellular and equiaxed crystals. The modified coating with 0.3wt.% Y 2 O 3 achieves a surface hardness of 568 HV 0.3 and a wear volume of 1,735.41 µm 3 , representing a 14.06% increase in hardness and a 51.16% reduction in wear volume compared to the undoped coating. Further increasing the Y 2 O 3 content from 0.3wt.% to 0.9wt.% gradually leads to the emergence of a coarser feather-like microstructure, characterized by a dendritic framework with inter-dendritic equiaxed crystals. Concurrently, both the hardness and wear resistance of the coating decrease. Nevertheless, all Y 2 O 3 -modified coatings surpass the undoped Fe45 coating in both hardness and wear resistance. Appropriate Y 2 O 3 doping effectively refines the Fe45 alloy coating’s microstructure and induces lattice distortion, thereby enhancing its hardness and wear resistance.